The invention is based on a closure system that is remotely controllable by transmitter signals for one or more locks of one or more openings, which can represent, for example a central locking system for the door locks and for the trunk lock of a motor vehicle and which is known per se to the expert from a high number of printed documents and prior uses.
A major problem in such methods is to avoid excessive ranges of the transmitter which facilitate thefts and occasionally also to avoid inferior ranges which make remote control more difficult or impossible. The invention relates to this major problem, namely the reliable automatic adaptive adjustment of such a range which makes thefts or burglaries more difficult and/or ensures comfortable remote control of lockable locks.
A remote controllable closure system, the receiver of which exhibits two different sensitivities, is known from DE-U 90 04 042. The first, high sensitivity is intended for continuous operation whereas the second, low sensitivity is intended for initialization or reinitialization of the system.
Furthermore, a remotely controllable closure system with variable transmitting power of the transmitter is known from DE-A1 33 41 900. In order to make it more difficult for an unauthorized person to record the transmitted code, the power is first low at the beginning of operation of the transmitter and is gradually increased with the corresponding length of operation. In this manner, the power is in each case gradually increased up to the value which is just adequate for enabling the closure system to operate.